What is the CVSS score of CVE-2025-21355?

CVE-2025-21355 has a CVSS 3.1 base score of 8.6 (High). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N. EPSS exploitation probability: 6.7%.

Which versions of Bing are affected by CVE-2025-21355?

Organizations using Missing Authentication for Critical Function in Microsoft Bing face significant risk from CVE-2025-21355, a missing authentication vulnerability rated CVSS 8.6.. A patch is available.

How to fix or mitigate CVE-2025-21355?

Within 7 days: Identify all affected systems and apply vendor patches promptly. Audit authentication configurations and rotate any potentially compromised credentials.

Bing CVE-2025-21355

HIGH

Missing Authentication for Critical Function (CWE-306)

2025-02-19 secure@microsoft.com

Microsoft Authentication Bypass Bing

8.6

CVSS 3.1 · NVD

Severity by source

NVD PRIMARY

8.6 HIGH

AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Changed

Confidentiality

High

Integrity

None

Availability

None

Lifecycle Timeline

Analysis Generated

Mar 28, 2026 - 18:27 vuln.today

Patch released

Mar 28, 2026 - 18:27 nvd

Patch available

CVE Published

Feb 19, 2025 - 23:15 nvd

HIGH 8.6

DescriptionCVE.org

Missing Authentication for Critical Function in Microsoft Bing allows an unauthorized attacker to execute code over a network

AnalysisAI

Missing Authentication for Critical Function in Microsoft Bing allows an unauthorized attacker to execute code over a network. Rated high severity (CVSS 8.6), this vulnerability is remotely exploitable, no authentication required, low attack complexity.

Technical ContextAI

This vulnerability is classified as Missing Authentication for Critical Function (CWE-306), which allows attackers to access critical functionality without authentication. Missing Authentication for Critical Function in Microsoft Bing allows an unauthorized attacker to execute code over a network Affected products include: Microsoft Bing.

RemediationAI

A vendor patch is available. Apply the latest security update as soon as possible. Require authentication for all sensitive operations, implement defense in depth.